The invention relates to a monolithic integrated RC-oscillator comprising only one external network which comprises a capacitor and a discharge circuit and which is arranged between a terminal of the integrated circuit and a point of reference potential, a charging circuit which can be switched on and off periodically being connected to said network, and said terminal being connected to a threshold circuit which has two switching thresholds and which causes the charging circuit to be switched on and switched off when the voltage across the capacitor of the network reaches the lower and the upper switching threshold, respectively.
An oscillator of this type is described in DE-OS No. 19 21 035. Oscillators of this type in the form of integrated circuits are frequently employed for generating a sawtooth voltage. Since the external frequency-determining elements are connected to only one terminal of the integrated circuit, oscillators of this type are also referred to as "1-pin oscillators". In such an oscillator the external discharge circuit generally comprises a resistor arranged in parallel with the capacitor. One edge (time interval T.sub.2) of the sawtooth waveform generated by such an oscillator is determined by the values of the external resistor and the external capacitor and the other edge (time interval T.sub.1) is also determined by the values of these two elements and by a charging current generated in the integrated circuit. In order to minimize the influence of the inevitable spread in the value of the charging current on the oscillator frequency, T.sub.2 is selected to be substantially longer than T.sub.1.
This has the disadvantage that the charging current during time interval T.sub.1 is larger, which may give rise to various problems (surge loading of the power supply, high current loads of the components, radio interference).